• The primary outcome measure will be the change in weight from baseline to endpoint using a random regression mixed effects model.
  

• Secondary outcome measures will include the change from baseline to endpoint in Body Mass Index (BMI) using a random regression mixed effects model, and the rate of change of weight and BMI.
  

Inclusion Criteria:Patients will meet the following criteria to be eligible to participate in the study:

• Diagnosis of Bipolar Disorder Type I, Type II, or NOS treated in ongoing therapy with atypical antipsychotic(s) and/or mood stabilizer(s) that have been implicated in causing weight gain (i.e. lithium, valproate, olanzapine, risperidone, quetiapine, aripiprazole).
• Age 18-65 years old
• Males; or nonpregnant, nonlactating females who are postmenopausal, surgically sterilized, or using a barrier method of contraception and have a negative pregnancy test
• Initial body mass index e 30 kg/m2, or e 27 kg/m2 and demonstrating or receiving treatment for metabolic consequences of overweight (fasting total cholesterol e 200mg/dL, fasting triglycerides e 250 mg/dL, or fasting blood glucose e 100 mg/dL).
• Stable medication regimen of at least one month
• Not have been hospitalized due to medical or psychiatric reasons during the past year from date of consent.
• Ability to understand and cooperate with study procedures
• Have signed a written informed consent prior to entering the study Exclusion Criteria:Patients may not participate in the study if they have any of the following conditions:
• One of the following DSM-IV Axis I diagnoses: delirium, dementia, amnestic and other cognitive disorders, schizophrenia, anorexia nervosa or bulimia, or substance abuse or dependence (active within the last month), abuse of illicit drugs (excluding marijuana) within the past month
• Antisocial personality disorder
• Medical complications of obesity such as diabetes, hypertension, hyperlipidemia, and cardiovascular disease unless followed by their own general medical practitioner who authorizes their participation in the trial, and continues to follow them medically and make necessary adjustments of concurrent antidiabetic, antihypertensive, antihyperlipidemic agents during the trial;
• Item 10 (Suicidal Thoughts) on the MADRS greater than or equal to 4
• Suicide attempt within the past three months
• Obesity of endocrine origin
• Seizure disorders
• Progressive neurologic or systemic disorders; HIV
• Other serious illnesses such as cardiac, hepatic (including cirrhosis), renal, respiratory, neurologic, or hematologic disease or glaucoma
• Hypothyroidism or hyperthyroidism unless adequately treated with TSH no more than 10% above or below the limits of the normal range.
• Administration of any investigational drug within 30 days prior to screening
• Allergy or hypersensitivity to ziprasidone
• Administration of clozapine in the prior three months
• Pregnancy within the past six months
• Patients will be discontinued from the study should they develop any significant adverse side effects that cannot be managed by dosage adjustment